Replace legacy Slack webhook with Slack App #6501
Description
As mentioned in https://gcdigital.slack.com/marketplace/A0F7XDUAZ-incoming-webhooks
Please note, this is a legacy custom integration - an outdated way for teams to integrate with Slack. These integrations lack newer features and they will be deprecated and possibly removed in the future. We do not recommend their use. Instead, we suggest that you check out their replacement: Slack apps.
We should look into https://docs.slack.dev to modernize our Slack integration with our Lambda function before they end support for legacy webhooks.
The SRE team can help us do the transition since they already went through it with the SRE Bot Slack App.